1. Field of the Invention
The present invention relates to a cooling system for an internal combustion engine.
2. Background Information
The idea of a cooling system for cooling an internal combustion engine (engine) has been known for some time. Japanese Unexamined Utility Model Application Publication No. 59-139516 discloses a cooling system that includes, for example, a heater, a radiator, a fan, and a cooling medium circulating apparatus. The heater is a heat exchanger configured to utilize heat generated by the engine. The radiator is a heat exchanger configured to discharge heat generated by the engine to an outside of the cooling system.
The cooling medium circulating apparatus is a device for circulating the cooling medium (e.g., a coolant comprising a mixture of antifreeze and water) and is connected to the engine, the heater, and the radiator. More specifically, the cooling medium circulating apparatus has a heater flow passage, a radiator flow passage, a bypass flow passage, a water pump, a thermostatic valve, a bypass valve, and a heater valve.
The heater flow passage is a flow passage through which coolant flows to and from the heater. The radiator flow passage is a flow passage through which coolant flows to and from the radiator. The bypass flow passage is a flow passage through which coolant is returned to the engine without passing through the heater or the radiator.
The water pump is a mechanical pump driven with power generated by the engine and is arranged to pump coolant to a water jacket of the engine. An inlet of the water pump is connected to the heater flow passage and the radiator flow passage.
The thermostatic valve is a valve contrived such that an open/close state thereof changes automatically in accordance with a temperature and is arranged in a connecting portion between the heater flow passage and the radiator flow passage. The heater valve is provided in the heater flow passage in a position between the thermostatic valve and the heater. The bypass valve is provided in the bypass passage.
When a temperature of the coolant is low, the thermostatic valve and heater valve are closed and the bypass valve is opened. In this state, since the coolant is returned to the engine through the bypass flow passage, heat generated by the internal combustion engine is not transmitted to the heater by the coolant. Consequently, the temperatures of the engine and the coolant rise readily and the time required for the engine to warm up can be shortened.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved cooling system for an internal combustion engine. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.